Symptoms of brain cancer occurring in the brain stem

The brainstem consists of three parts from top to bottom: the midbrain, pons, and medulla oblongata. It is located in the posterior cranial fossa, on the slope in front of the foramen magnum. The focal symptoms of brain cancer occurring in the brainstem vary depending on the location of the tumor.

1. Midbrain tumor

Since the tumor here can easily block the aqueduct, symptoms of increased intracranial pressure may appear in the early stage. There are also cases where the first symptoms are mental and intellectual changes, which may be related to the involvement of the reticular structure. The manifestations are: ① Crossed oculomotor nerve hemiplegia syndrome, the lesion is located at the base of the cerebral foot, and the oculomotor nerve is paralyzed on the affected side, and the upper and lower limbs and facial and tongue muscles on the opposite side are centrally paralyzed. ② Quadrigeminal syndrome, manifested by ptosis, upward gaze paralysis, fixed pupils, loss of light response, inability to converge, etc. ③ Benedikt syndrome, manifested by deafness, oculomotor nerve paralysis on the affected side, increased muscle tension and tremor on the opposite side.

2. Pontine tumor

It accounts for more than half of all brainstem tumors and is more common in children. In the early stage, children often present with diplopia and easy falls as the first symptoms; in adults, dizziness and ataxia are often the first symptoms. It often manifests as damage to one side of the pons, including facial nerve cross palsy. If the lesion is located on one side of the lower half of the pons, it will cause peripheral facial palsy on the affected side with contralateral limb hemiplegia.

3. Medullary tumors

The first symptom is often vomiting, which is easily misdiagnosed as neurotic vomiting or neurosis. It manifests as varying degrees of dizziness, headache, cranial nerve paralysis symptoms, such as difficulty swallowing, choking when eating, nasal speech, and inability to extend the tongue. When the tumor involves both sides, it is a true bulbar palsy syndrome, accompanied by bilateral limb movement, sensory disorders and varying degrees of spastic paraplegia. There may be irregular breathing in the early stage of the disease, and dyspnea or failure in the late stage.